Achievable Rates for Massive MIMO Relaying Systems With Variable-Bit ADCs/DACs

Focusing on massive multiple-input and multiple-output (MIMO) relaying systems with variable resolution analog- to-digital converters (ADCs) and digital-to-analog converters (DACs), we derive the exact and approximate closed-form expressions for the achievable rate over Rayleigh fading channels. Numerical results reveal that the low-resolution DACs degrade the system performance much more than the low-resolution ADCs, and that the low-resolution ADCs and DACs achieve better energy efficiency. Moreover, provided that the total number of quantization bits is constrained, we find that the achievable rate is optimal when all ADCs and DACs adopt the same quantization bits from the perspective of statistic.